linux-kernel - Re: [PATCH] Documentation: dt: mtd: replace "nor-jedec" binding with "jedec,spi-nor"

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Date:	Thu, 21 May 2015 11:39:08 +0200
From:	Geert Uytterhoeven <geert@...ux-m68k.org>
To:	Rafał Miłecki <zajec5@...il.com>
Cc:	Brian Norris <computersforpeace@...il.com>,
	"linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Stephen Warren <swarren@...dotorg.org>,
	Marek Vasut <marex@...x.de>,
	linux-spi <linux-spi@...r.kernel.org>
Subject: Re: [PATCH] Documentation: dt: mtd: replace "nor-jedec" binding with "jedec,spi-nor"

Hi Rafal,

On Thu, May 21, 2015 at 11:31 AM, Rafał Miłecki <zajec5@...il.com> wrote:
> On 21 May 2015 at 10:58, Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
>> On Thu, May 21, 2015 at 10:50 AM, Rafał Miłecki <zajec5@...il.com> wrote:
>>>>>> I think your comments suggest that I shouldn't be removing "spi-nor"
>>>>>> from m25p_ids[] nor from this block:
>>>>>>
>>>>>>         if (data && data->type)
>>>>>>                 flash_name = data->type;
>>>>>>         else if (!strcmp(spi->modalias, "spi-nor"))
>>>>>>                 flash_name = NULL; /* auto-detect */
>>>>>>         else
>>>>>>                 flash_name = spi->modalias;
>>>>>>
>>>>>> So it stays in both m25p_ids[] and .of_match_table.
>>>>>>
>>>>>> I suppose that can work. It then allows people to do weird stuff like:
>>>>>>
>>>>>>         compatible = "idontknowwhatimdoing,spi-nor";
>>>>>>
>>>>>> in their device tree. But other than that, there's not much downside I don't
>>>>>> think.
>>>>>
>>>>> It sounds like a reasonable solution. I guess there isn't a perfect
>>>>> one. Even if we decide to go for sth like "jedec-spi-nor", there
>>>>> always will be a chance of someone using
>>>>> compatible = "idontknowwhatimdoing,jedec-spi-nor";
>>>>> So if you rework your patch to leave "spi-nor" support in m25p_ids and
>>>>> conditions block, it should be OK.
>>>>
>>>> Typically platform devices just use the driver's name. Hence IMHO there's
>>>> no need to add a shiny new spi-nor device name.
>>>>
>>>> So what's wrong with using "m25p80", and treating that as auto-detect iff
>>>> !spi->dev.of_node?
>>>
>>> Treating "m25p80" as auto-detect triggering string won't allow
>>> platform to *force* "m25p80" flash type if there ever appears to be
>>> needed. Maybe it's unlikely, but it still sounds like a bit bad design
>>> for me.
>>
>> To force m25p80 flash, you set flash_platform_data.type to "m25p80"?
>
> Oh, I think I got lost in the way m25p80 is probed. Is it handled by
> spi_board_info and its "modalias"?

Indeed.

> Could I leave flash_platform_data.type set to NULL and still have m25p80 probed?

Yes, that case is the final "else" branch above.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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